graphql: fix error messages for output types mismatch

cartridge/graphql/execute.lua

@@ -194,12 +194,16 @@ local function completeValue(fieldType, result, subSelections, context, opts)
   end
 
   if fieldTypeName == 'List' then
-    local innerType = fieldType.ofType
-
-    if type(result) ~= 'table' then
-      error('Expected a table for ' .. innerType.name .. ' list')
+    if not util.is_array(result) then
+      local resultType = type(result)
+      if resultType == 'table' then
+        resultType = 'map'
+      end
+      local message = ('Expected %q to be an "array", got %q'):format(fieldName, resultType)
+      error(message)
     end
 
+    local innerType = fieldType.ofType
     local values = {}
     for i, value in ipairs(result) do
       values[i] = completeValue(innerType, value, subSelections, context)
@@ -213,6 +217,10 @@ local function completeValue(fieldType, result, subSelections, context, opts)
   end
 
   if fieldTypeName == 'Object' then
+    if type(result) ~= 'table' then
+      local message = ('Expected %q to be a "map", got %q'):format(fieldName, type(result))
+      error(message)
+    end
     local completed = evaluateSelections(fieldType, result, subSelections, context)
     setmetatable(completed, serializemap)
     return completed

cartridge/graphql/util.lua

@@ -190,7 +190,9 @@ end
 --- case)
 --- @return[2] `false` otherwise
 local function is_array(table)
-    check(table, 'table', 'table')
+    if type(table) ~= 'table' then
+        return false
+    end
 
     local max = 0
     local count = 0

test/integration/graphql_test.lua

@@ -281,7 +281,7 @@ g.test_reread_request = function()
 end
 
 
-g.test_enum = function()
+g.test_enum_input = function()
     local server = cluster.main_server
 
     server.net_box:eval([[
@@ -343,6 +343,53 @@ g.test_enum = function()
     end)
 end
 
+g.test_enum_output = function()
+    local server = cluster.main_server
+
+    server.net_box:eval([[
+        package.loaded['test'] = package.loaded['test'] or {}
+        package.loaded['test']['test_enum_output'] = function(_, _)
+            return {value = 'a'}
+        end
+
+        local graphql = require('cartridge.graphql')
+        local types = require('cartridge.graphql.types')
+
+        local simple_enum = types.enum {
+            name = 'simple_enum_output',
+            values = {
+                a = { value = 'a' },
+                b = { value = 'b' },
+            },
+        }
+
+        local object = types.object({
+            name = 'simple_object',
+            fields = {
+                value = simple_enum,
+            }
+        })
+
+        graphql.add_callback({
+            name = 'test_enum_output',
+            args = {},
+            kind = object,
+            callback = 'test.test_enum_output',
+        })
+    ]])
+
+    t.assert_equals(
+        server:graphql({
+            query = [[
+                query {
+                    test_enum_output{ value }
+                }
+            ]],
+        variables = {}}
+        ).data.test_enum_output.value, 'a'
+    )
+end
+
 g.test_unknown_query_mutation = function()
     local server = cluster.main_server
     t.assert_error_msg_equals(
@@ -687,6 +734,105 @@ g.test_custom_type_scalar_variables = function()
     end)
 end
 
+g.test_output_type_mismatch_error = function()
+    local server = cluster.main_server
+
+    server.net_box:eval([[
+        package.loaded['test'] = {}
+        package.loaded['test']['callback'] = function(_, _)
+            return true
+        end
+
+        package.loaded['test']['callback_for_nested'] = function(_, _)
+            return { values = true }
+        end
+
+        local graphql = require('cartridge.graphql')
+        local types = require('cartridge.graphql.types')
+
+        local obj_type = types.object({
+            name = 'ObjectWithValue',
+            fields = {
+                value = types.string,
+            },
+        })
+
+        local nested_obj_type = types.object({
+            name = 'NestedObjectWithValue',
+            fields = {
+                value = types.string,
+            },
+        })
+
+        local complex_obj_type = types.object({
+            name = 'ComplexObjectWithValue',
+            fields = {
+                values = types.list(nested_obj_type),
+            },
+        })
+
+        graphql.add_callback({
+            name = 'expected_nonnull_list',
+            kind = types.list(types.int.nonNull),
+            callback = 'test.callback',
+        })
+
+        graphql.add_callback({
+            name = 'expected_obj',
+            kind = obj_type,
+            callback = 'test.callback',
+        })
+
+        graphql.add_callback({
+            name = 'expected_list',
+            kind = types.list(types.int),
+            callback = 'test.callback',
+        })
+
+        graphql.add_callback({
+            name = 'expected_list_with_nested',
+            kind = types.list(complex_obj_type),
+            callback = 'test.callback_for_nested',
+        })
+    ]])
+
+    t.assert_error_msg_equals('Expected "expected_nonnull_list" to be an "array", got "boolean"', function()
+        return server:graphql({
+            query = [[
+                query {
+                    expected_nonnull_list
+                }
+            ]]})
+    end)
+
+    t.assert_error_msg_equals('Expected "expected_obj" to be a "map", got "boolean"', function()
+        return server:graphql({
+            query = [[
+                query {
+                    expected_obj { value }
+                }
+            ]]})
+    end)
+
+    t.assert_error_msg_equals('Expected "expected_list" to be an "array", got "boolean"', function()
+        return server:graphql({
+            query = [[
+                query {
+                    expected_list
+                }
+            ]]})
+    end)
+
+    t.assert_error_msg_equals('Expected "expected_list_with_nested" to be an "array", got "map"', function()
+        return server:graphql({
+            query = [[
+                query {
+                    expected_list_with_nested { values { value } }
+                }
+            ]]})
+    end)
+end
+
 function g.test_error_extensions()
     local request = {
         query = [[mutation($uuids: [String!]) {